(1) Field of the Invention
This invention relates generally to the method of making an absorbent pad, and particularly on the method of continuously applying adhesive for securing elastic bands thereto.
(2) Prior Art
Elastic ribbon should be applied in a stretched condition to the leg portions of absorbent undergarments such as babies' diapers or adult continent briefs. The elastic ribbon is applied in a stretched condition only in that leg portion so as to cause gathers therein. The remaining portion of the elastic extending over the balance of the absorbent pad is not adhered to the pad, so that that portion of the pad will not gather. In the manufacture of diapers and absorbent pads as well as adult incontinent briefs, an elastic band is continuous form is placed against an unrolled web or a continuous web or backing material. The elastic band has adhesive applied thereon in discontinuous portions therealong, so as to effectuate the attachment of the bands to the backing material along the leg portions thereof. Such an apparatus and method for same is shown for example, in U.S. Pat. No. 4,081,301. Adhesive, as shown in this Patent, may be applied in thin strands on the elastic or as individual dots of adhesive on the elastic. The elastic band is then applied to diaper material as the diaper material proceeds along the assembly processes. As the individual backing sheets are cut and severed from one another, the stretched elastics are also severed. The portion of the elastics that are glued or bound by adhesive to the backing sheet of the diaper cause the diaper in that portion to gather. The unattached portion of the rubber band merely remain in the flaccid state adjacent the absorbent pad. U.S. Pat. No. 4,371,417 shows an apparatus for inserting elastic strips onto diapers for stretching and relaxing predetermined lengths of the elastic strips as they are secured to the diaper material. U.S. Pat. No. 4,297,157 shows a rather complicated apparatus for placing elastic strips under tension, onto garments. An annular array of linkages and arms are used to apply the elastic to discrete areas adjacent the leg openings of diapers.
Another Patent showing the adhesion of elastic to disposable diapers is shown in U.S. Pat. No. 4,585,507. An oscillating fork means V-folds longitudinally spaced portions of an adhesive equipped ribbon against the backing sheet of a diaper. The V-shaped longitudinally spaced portions do not adhere to their respective portions of diaper and so fail to cause the required gathering thereof. U.S. Pat. No. 4,578,133 shows a method and apparatus for applying strips of elastic to a web of diaper material. The apparatus is very complicated and requires a difficult method of applying the strips to the web of material. Two other recent disclosures are shown in U.S. Pat. Nos. 4,572,043 and 4,574,022 which again also show rather complicated apparatus for applying discrete lengths of elastic material to a moving web of backing sheet. In U.S. Pat. No. 4,525,229 an elastic band is attached to a tape which is attached to the web forming the backing sheet of the diaper. U.S. Pat. No. 4,556,596 shows self adhering elastic strips applied to a flexible base material. U.S. Pat. No. 4,543,141 shows another arrangement for longitudinally folding portions of the ribbon prior to its disposition against a base sheet to immobilize those portions of the ribbon. U.S. Pat. No. 4,523,969 shows an arrangement for gripping elastic ribbon at several points and stretching same prior to its application against a base sheet comprising the bottom portion of the diaper. U.S. Pat. No. 4,507,163 shows a method of feeding adhesive onto an elastic before it is applied to the base of a diaper.
Though the collection of prior art is numerous, and often very complicated, none of it appreciates a simpler method of performing the same operation.
Thus it is an object of the present invention to provide a method of attaching the elastic to a web not shown in the art.
It is a further object of the present invention to provide a controllable, continuous application of adhesive to a backing sheet of a diaper or an adult brief.